brewing a 6 gallon Pliney The Elder clone tomorrow. I have 15lbs of grain. How much water will i need to use if i am batch sparging? Thanks
That depends on your system.
On my system, if I planned for a 60 minute boil (boil off of 1.2 gallons per hour), I would use 5.5 gallons in the mash, and sparge with 3.5 gallons. That would give me about 3.25 gallons of first runnings and 3.5 gallons of second runnings, accounting for the 1.8 gallons of grain absorption and the 1/2 gallon of wort lost in the mash tun resulting in 6.75 gallons into the kettle. After boil off and about a quarter gallon lost in the kettle (though that is probably higher with a hop heavy recipe like Pliny), I’d get 5 gallons in the fermentor.
Enough to hit your boil volume. After your mash runoff, measure how much you get. Subtract that from the boil volume you want. The answer is how much sparge water to use.
Enough to hit your boil volume. After your mash runoff, measure how much you get. Subtract that from the boil volume you want. The answer is how much sparge water to use.[/quote]
Denny is a wise man. (but we all knew that 
). My 1st couple AG batches I spent a lot of time calculating my sparge amount. And with one batch wound up with almost 8 gallons to boil down to the 5.5 that I wanted. Took a LOOOng time and I had to use an extra BK to boil the excess. Then I figured out what Denny knew already. Boil times are much more sane since.
By my calculations, you’ll need to strike with about 5.25 gallons at roughly 170 F (assuming you do not preheat the mash tun). Then sparge with 3.5 gallons at about 195 F for simultaneous mashout. This way you will get just slightly more than 7 gallons to arrive at your desired 6 gallons after the boil. This assumes a standard turkey fryer sized kettle.
If you are using a relatively large diameter keggle, then you would need to use a little more water to account for a higher boiloff rate – maybe 5.5 gallons first then 3.75 gallons sparge, something like that.
